Fan



y 5, 1953 H. TAYLOR, JR 2,637,486

FAN

Filed Dec. 29, 1951 r 2 sHEETs -sHEET 1 y 5, 1953 w. H. TAYLOR, JR 2,637,486

FAN

Filed Dec. 29, 1951 2 SHEETS-SHEET 2 n a large volume of heated air t installation-of a fan.

Patented May 5, 1953 I 4m; W sto. This invention relates v s and relates v:more:1:.articularly nections at the axial inletsepilsuch e gro setmitting secondary pair, -.-the 1- einto ,,,-With0ut adverselyi-afiectihgivthe fipwtgi primary air rm amaximumi eriormaneetthe axial n1 .P a tan-ishould be nicely strearnflined WithAQ 9 structions-,to-,-fiow extendingithereintot, .I lowaver, ior some duties, it, isn necessary to sup-ply seuondvary aiminto-suchan;inle'athrch1gh. aSupDly: m t suchsupp y ducts, when h ttusediip supplying secondaryaim-have extended into the tan inlets, and. haveainterfered" with: the flow f p ry ain. ".An example .ot such a. dutyv i the Wsupplytof air through an airaheater into the combustionwchamberi ,oi t3, .;.steam powers 1. plant. w1181 .Hair supplied thy-a fan. isgdrawnnfrom; n. a iparatus room inrwhich the fan-sislocate,d, ,nd -blown- ;:through thei interiorsagf .iheatj-qxtlhdng i itubes over the exteriersoftyvhich, therfllle gases of; the plant passiciAt.v low plant loads, (the temperature of the inlet header sheet of the air t iheatermaysfall below th dewipoint temperature :.-Of the corrosive. vapors in thetfiue gas es resultwing in the condensationofc-sutlrxap lts on the inlet sheet z-iwith. resulting,- corrosion. Accordingly, it isthe practice at low plant loads to recirculate heated air-'- irom the outletao-fflthe air heater intqthe inlet p f the i r gnaintaining ah the heat lnthe past, recirculation have exteifdedlintgv the inlets of the fansy and fhave'finte with the fiow of primary 'a' plant loads, when no recirQP The. Geissler et a1. Patent No 2 47654331 I elfiective Way of supply m nlet of a fan without aifi v s tih fan nentheei ra h da air is discontinued, but requires a special form of duct for accomplishingithis such a duct usually having to be fabricated and installed after This inventiori provides ct gconrie'ct 11$ for pplyihg secondary'air"or'other gases'fi'rito the axial inlet of a fan, which are made an integral part of the fan at the time it is fabricated, irequiring only the connection of an ordinary secondary air duct to the fan when the fan is installed. This invention is particularly suited for use with centrifugal fans having spin vane such as are disclosed in the H. F. Hagen Patent No. 1,989,413, and a feature of this invention is that the secondary air as Well as the primary air is acted upon by the spin vanes.

An object of this invention is to provide at the axial inlet of a fan of the forced draft type, duct 1,. tan ofdtheufercediidraft-ntynelihaliihe .t

anaemiaeater fere with the now of pr inlet.

5 eiencettolthe dimv i aDLW MWEig.i=l.; isia partialside elevat n, forced draft fan embodying 1. pantialtend ele i J; The fan illustrated is a $10,1

scrollihousing J 9 around It is; mounted ,on the .iiotarv; eend bearinesill. only -I.0ne..,Qf, The-tan "has, gtheiee ntrally lo'eated, outlet t ,Q "filer convenienceiv'ot illustration onlygon' 'of the fan Wiieen which would-b usediis' sh wn.

Jan wh el-.1

i v. v,

QiaI'QHIlQ theisllaft [2,2 1

amt tingmec anismid wiandiai kat taphed to, the ring 21' opposite" he m ic rt en 29-h:

a l v. Ar inner plate gfi ex en g around ssage 21 to the spin vanes'lT; and 1s secured by the fan inlet, and discharges into the inlet passage through the constricted passage 28. This causes a static pressure to be built up in the duct 23 resulting in uniform flow of secondary air at all points around the fan inlet passage, and preventing short-circuit flow into the inlet passage at points above the inlet passage, and starved flow into the lower portion of the inlet passage.

The constricted passage 28 is located to discharge through the space occupied by the spin vanes l7 whereby the secondary air as well as the primary air is acted upon by the spin vanes when volume reduction is desired.

Since the heated, secondary air passes over all of the spin vanes, their thermal expansion is uniform. In prior constructions where secondary air ducts protruded into the inlets of fans having spin vanes, only those few vanes at the outlets of the secondary air ducts were heated,-

resulting in uneven expansion and binding.

Utilizing this invention, the secondary air is --mixed with the primary air uniformly around the fan inlet passage without Stratification.

The damper 30 in the upper portion of the duct 23 can be used for separately varying the volume of secondary air, or for closing the duct 23 when recirculation is not desired.

In operation, with the damper 30 closed, the

-fan operates as a conventional forced draft fan without a recirculated air connection since the secondary air duct does not protrude into the inlet passage and affect the fiow of primary air.

With the damper open, the secondary air stream merges smoothly into the primary air stream,

a both streams being acted upon by the spin vanes trated since modifications may be suggested by those skilled in the art, without departure from the essence of the invention.

What I claim as my invention, is:

1. In a fan having a fan wheel and an inlet shroud forming a converging axial inlet passage for primary air into the wheel, and spin vanes pivoted in said passage on axes oblique to the axis ofthe' wheel, the combination of means forming a secondary air passage extending circumferentially around said inlet passage, and

means forming a circumferenti-ally extending constricted outlet from said secondary passage into said converging passage, said vanes having outer portions extending across said constricted outlet.

2. In a fan having a fan wheel and an inlet shroud forming a converging axial inlet passage into said wheel for primary air, said shroud having outer ends extending substantially perpendicular to the axis of said wheel, the combination of means forming a secondary air'passage extending circumferentially around said converging passage, said means including an inner wall attached to said outer ends of said shroud and extending substantially perpendicular to said axis, and including an outer wall spaced from said inner wall and extending substantially parallel thereto, and means forming a circumferentially extending constricted outlet from said secondary passage into said converging passage.

3. The invention claimed in claim 2 in which spin vanes are pivoted in the converging passage, and have outer portions which extend across the constricted outlet.

4. The invention claimed in claim 3 in which the last mentioned means includes an annular plate having an outer portion secured to said outer wall, and having an inner portion curved inwardly towards said shroud.

5. The invention claimed in claim 2 in which the last mentioned means includes an annular plate having an outer portion secured to said outer wall, and having an inner portion curved inwardly towards said shroud.

6. In a fan having a fan wheel, and a shroud forming an axial inlet passage into said wheel for primary air, said shroud having an outwardly turned outer portion extending substantially perpendicular to the axis of said wheel, the combination of means forming a secondary air passage extending around the outer portion of said inlet passage, said means including an inner wall attached to said outer portion of said shroud, and including an outer wall spaced from said inner wall, said outer wall having a circular opening centrally around said axis, and means forming a circumferentially extending constricted outlet from said secondary passage into said inlet passage, said last mentioned means including an annular plate secured to said outer wall around said opening, said plate having an inner portion curved inwardly towards said shroud.

7. The invention claimed in claim 6 in which spin vanes are pivoted in said inlet passage and have outer portions extending across said outlet.

WILLIAM H. TAYLOR, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,467,306 Carrier Sept. 11, 1923 1,575,447 Moore Mar. 2, 1926 1,787,655 Anderson Jan. 6, 1931 1,989,413 Hagen Jan. 29, 1935 2,100,489 Richardson Nov. 30, 1937 2,274,033 Booth Feb. 24, 1942 2,287,822 Odor et al June 30, 1942 1 2,476,543 Geissler et al. July 19, 1949 FOREIGN PATENTS Number Country Date 337,798 Italy Mar. 13, 1936 643,846 Germany Apr. 19, 1937 

